The Internet provides access to a wide range of resources. For example, web pages for particular subjects are accessible over the Internet. Access to these resources presents opportunities for advertisements to be provided with the resources. A web page can, for example, include advertisement slots in which advertisements can be presented. These advertisements slots can be defined for presentation with a web page, for example, in a pop-up window. The advertisements slots can also be defined in the web page.
An advertiser creates an advertisement campaign describing the advertisement and includes a link to a landing page describing the advertisement. When the advertisement is selected by the user, the user is directed to the landing page. The landing pages can include any type of content, whether it is content related to the advertisement or content unrelated to the advertisement. For example, the landing page may include pornographic material that is unsuitable to be used as a landing page. The landing pages can also include malicious spyware or other types of content that may cause harm to a user's computer.